Diabetes mellitus is a metabolic disease primarily characterized by a chronic hyperglycemic state due to a lack of insulin action. The treatment of diabetes is generally by drug therapy together with diet therapy and exercise therapy. Examples of oral hypoglycemic agents in use, which are a class of therapeutic drugs for diabetes, include biguanide agents and thiazolidinedione agents that improve insulin resistance; sulfonylurea agents and glinide drugs that promote insulin secretion from pancreatic β cells; and α-glucosidase inhibitors that inhibit sugar absorption.
However, it is reported that biguanide agents have adverse side effects such as digestive symptoms and lactic acidosis; thiazolidinedione agents have adverse side effects such as weight gain and edema; sulfonylurea agents and glinide drugs have adverse side effects such as hypoglycemia or secondary failure due to long-term use; and α-glucosidase inhibitors have adverse side effects such as diarrhea. Therefore, development of an oral hypoglycemic agent which can address such problems is desired.
Furthermore, in recent years, piperidine compounds have been developed as oral hypoglycemic agents having new structures (see, for example, Patent Literature 1 to 4). Still further, oxadiazole compounds have been disclosed (see, for example, Patent Literature 5 or 6).